Electron gun support and shielding means

ABSTRACT

IMPROVED MEANS ARE PROVIDED FOR SUPPORTING AND SHIELDING A COMPACT ELECTRON GUN WITHIN THE NECK PORTION OF A CATHODE RAY TUBE. AN ANNULAR MEMBER, DIMENSIONED TO CLOSELY APPROACH THE INTERNAL DIAMETER OF THE NECK, IS FORMED FOR ATTACHMENT TO AT LEAST THREE SPACED-APART STEM LEADS. AN OPEN-ENDED CLOSED-WALL PORTION, UPSTANDING FROM THE CENTRAL APERTURE OF THE ANNULAR MEMBER, IS DIMENSIONED TO ENCOMPASS THE WHOLE OF THE ELECTRON GUM THEREIN. GUN RETENTION MEANS ARE EMPLOYED TO HOLD THE GUM WITHIN THE CLOSED-WALL PORTION IN A MANNER THAT THE FORWARD END OF THE GUN IS POSITIONED AT THE TERMINAL THEREOF.

Feb. 13, 1973 o. L. SAY

ELECTRON GUN SUPPORT AND SHIELDING MEANS Filed Aug. 31, 1971 INVENTOR. 110mm 1.. 5m

ATTOR N EY United States Patent M US. Cl. 313-82 R 2' Claims ABSTRACT OF THE DISCLOSURE Improved means are provided for supporting and shielding a compact electron gun within the neck portion of a cathode ray tube. An annular member, dimensioned to closely approach the internal diameter of the neck, is formed for attachment to at least three spaced-apart stem leads. An open-ended closed-wall portion, upstanding from the central aperture of the annular member, is dimensioned to encompass the whole of the electron gun therein. Gun retention means are employed to hold the gun within the closed-wall portion in a manner that the forward end of the gun is positioned at the terminal thereof.

CROSS-REFERENCE TO RELATED APPLICATION This application contains matter disclosed but not claimed in a related application filed concurrently herewith and assigned to the assignee of the present invention. This related application is S.N. 176,502, filed Aug. 31, 1971, Color Cathode Ray Tube.

BACKGROUND OF THE INVENTION This invention relates to means for supporting and shielding an electron gun and more particularly to means for supporting, positioning and shielding a compact electron gun in the neck portion of a cathode ray tube.

Multi-element electron guns, as employed, for example, in cathode ray tube applications, are conventionally fabricated by utilizing several spaced apart insulative rods to integrate a plurality of sequentially related electrodes into the desired structure. In gun assemblies supplying a plurality of electron beams, the gun construction is more complicated since a plurality of individual guns are generally combined into a single assembly. Regardless of the complexity of the gun assembly, it has been usual procedure to position the respective assembly within the neck portion of the tube envelope by securing related connective and supportive stem leads to substantially lower portions of the assembly. Centering of the gun structure or lateral placement within the neck is normally effected by metallic snubbers or ceramic positioning means oriented at the forward or upper portion of the assembly. The rear or bottom portion of the gun structure, while afiixed to a plurality of leads, is generally not rigidly oriented to withstand severe lateral shock. The normal gun positioning means and procedure affords limited shielding characteristics.

OBJECTS AND SUMMARY OF THE INVENTION It is an object of the invention to reduce the aforementioned disadvantages and to provide improved means for supporting and shielding an electron gun in a cathode ray tube.

A further object is to provide supporting and shielding means for an electron gun in a manner to impart improved lateral support.

An additional object is to provide improved supporting and shielding means for a compact gun assembly to facilitate the production of an improved cathode ray tube.

The foregoing objects are achieved in one aspect of the invention by the provision of improved means for supporting and shielding a compact electron gun within the neck portion of the tube envelope. The supporting and shielding means has an annular member diametrically dimensioned to closely approach the internal diameter of the neck and is formed to be attached to at least three spaced-apart leads extending inwardly from the stern closure portion of the envelope. A substantially open-ended closed wall portion, upstanding from the central aperture in the annular member, is dimensioned to shield and accommodate the whole of the compact electron gun therein. The terminal end of the closed-wall portion has a ledge formed to instand from the perimeter thereof to provide a stop for the terminal portion of the encompassed electron gun. Gun retaining means are formed to fit Within the closed wall portion to hold the compact electron gun structure therein in a manner that the forward end of the gun is positioned against the terminal ledge of the closedwall portion.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view showing the electron gun support and shielding means positioned in the neck portion of a cathode ray tube taken along the line 11 of FIG. 2;

FIG. 2 is a plan view of the electron gun support and shielding means as taken along the line Z -Z in FIG. 1; and

FIG. 3 is an enlarged perspective view of a portion of the support and shielding means illustrating in greater detail one of the resilient fingers extending beyond the periphery thereof.

DESCRIPTION OF THE PREFERRED EMBODIMENT For a better understanding of the present invention, together with other and further objects, advantages and capabilities thereof, reference is made to the following specification and appended claims in connection with the aforedescribed drawings.

With reference to the drawings, there is shown in FIG. 1 a sectional view illustrating a portion of the neck region 11 of a cathode ray tube 13 having a longitudinal axis 14 extending therethrough. Terminally sealed to the neck portion 11 is a conventional stem wafer or neck closure portion 15 which has a plurality of connective and support leads 17 sealed therein.

Oriented within the neck portion 11 is an electron gun supporting and shielding means 19 which is supportively attached, as by welds 21, to the terminal portions 23 of at least three appropriate spaced-apart leads 17, thereby desirably orienting the gun assembly 24. In referring to FIGS. 1 and 2, the supporting and shielding means 19 is shown to include an annular member 25 having an inner periphery 27 defining a central aperture and an outer periphery 29 defining the perimetric boundary thereof. The area between the aforementioned peripheries 27 and 29 constitutes the annular planar surface 31. This annular member 25 has an overall diametric dimension d which closely approaches the internal diameter d of the neck portion 11 to facilitate insertion of the support means 19 into the neck portion while providing lateral support for the gun assembly 24 to prevent transverse shifting thereof. A skirt portion 33 is formed around the outer periphery 29 extending toward the neck closure portion 15. To further achieve the above-mentioned lateral support, a plurality of at least three spaced apart dimples 35 are formed in the skirt portion 33 in a manner to protrude outward beyond the outer periphery 29 to more closely approach the internal diameter d of the neck portion. Since the manufacturing tolerances inherent in the fabrication of the annular member 25 and the neck portion 11 may, on occasion, be additive or subtractive in a manner to allow excessive spacing between the dimples 35 and the neck interior surface 37, it is preferred, in adequately coping with such instances, to employ expansive means to achieve the desired transverse support.

For example, a plurality of at least three spaced-apart substantially metallic resilient fingers 39 are attached to the skirt portion 33 of the annular member 25 in a manner to extend outward beyond the outer periphery 29 to effect positive positional contact between the annular support member 25 and the wall of the neck portion 11. This construction advantageously provides positive lateral placement in the region of vertical support. An enlarged detail of an example of a resilient finger 39 is shown in FIG. 3. To reduce the pickup of an excessive amount of induction heat during tube processing and degassing, it is desirable to have at least one slit 41 formed in the skirted annular member 25 extending from the outer periphery 29 through the skirt portion 33 into the planar surface 31 toward the axis 14. While one slit 41 will prevent a pick-up of induction heat, it is preferable to radially dispose a plurality of spaced apart slits to effect a uniform heat sink around the electron gun assembly 24 during processing.

Upstanding from the inner periphery 27 of the annular member 25 is a substantially upstanding collar 43 to which a compatible substantially upstanding open-ended closedwall portion 45 is integrally joined. This closed-wall portion 45 is dimensioned to shield and accommodate the whole of the compact electron gun assembly 24 therein. For example, a typical compact gun assembly advantageously employing planar electrodes and emitting one or a plurality of electron beams may be of the type basically disclosed in S.N. 126,609 by A. D. Johnson et al. and assigned to the assignee of the present invention.

The closed-wall portion 45 has a ledge 47 formed at the terminal end 49 to instand from the perimeter thereof to form a stop for the terminal portion of the encompassed electron gun assembly 24. The compact gun is confined within the closed-Wall portion by gun retaining means 51; such means being formed to fit and compatibly telescope within the closed-wall portion, and be affixed therein, at the end region related to the annular member 25. The retaining means 51 is in the form of a ring or a plurality of tabs shaped to be abutted against the bottom portion of the gun structure 24.

The exemplary tube embodiment partially shown in FIG. 1 illustrates a two beam cathode ray tube 13 employing magnetic focusing. A conductive coating 53, extending into the neck portion 11 from the screen area, not shown, is at screen potential in the operating tube. The electron gun 24 encompassed by the metallic supporting and shielding means 19 includes a common cathode or thermionic electron source 55 retained in a ceramic positioner '7. Sequentially oriented ahead of the emissive area of the cathode 55 are a plurality of planar type electrodes, as for example, 58, 59, and 59' not fully detailed, which are separated fromione another by several discrete insulative means 61. As shown, sequential planes 58 and 59 have insulative provisions therein to effect individual control of the plural electron beams passing therethrough. The several electrodes and respective insulative means of the gun structure are integrated by a plurality of spaced apart insulative integration means such as bolts 63. Since the final electrode 59' abutts the ledge 47, the metallic supporting and shielding means 19 is at final anode potential which is lower than the screen potential on the neck disposed coating 53. Consequently, an electron diverging lens 65 partially indicated, is formed ahead of the gun assembly and influences the respective beams 4 52 and 52. In this usage the field of the electron lens 65 surrounding the encompassed gun structure should be circumferentially constant, therefore, the upstanding closed-wall portion 45 is of substantially cylindrical cross section.

The skirted annular member 25 provides effective shielding for the glass sidewall area adjacent the neck coating 53, preventing cathode and heater sublimation materials from migrating to that area. Since the whole compact gun assembly 24 is encompassed by the supporting and shielding means 19 which is at final anode potential, the conditions for forming the electron lens 65 are markedly enhanced.

Thus, there is provided an improved supporting and shielding means for a CRT compact electron gun that promotes adequate lateral support to the gun assembly while effecting advantageous shielding characteristics.

While there has been shown and described what are at present considered the preferred embodiments of .the invention, it will be obvious to those skilled in the art that various changes and modifications may be made therein without departing from the scope of the invention as defined by the appended claims.

What is claimed is:

1. In a cathode ray tube having an encompassing en velope with a longitudinal axis extending therethrough, means for supporting and shielding a compact multiple electrode electron gun in the neck portion of said tube relative to a neck closure portion having a plurality of leads extending therefrom, said supporting and shielding means comprising:

an annular member having an inner periphery defining a central aperture and an outer periphery defining the perimetric boundary with the area therebetween constituting the planar surface of said annular member, said annular member having an upstanding collar perimetrically formed around said inner periphery in a manner to extend away from said neck closure portion and an over-all diametric dimension approaching the internal diameter of said neck portion, said annular member having a skirt portion formed around the outer periphery thereof extending toward and spaced above said neck closure portion and supportively attached to at least three of said leads spaced apart and extending inwardly therefrom, said skirted annular member having at least one slit formed therein in a manner to extend from said outer periphery through said skirt into said planar surface toward said axis;

a substantially cylindrical open-ended closed-wall por-' lar defining said central aperture in said annular member, said closed-wall portion being dimensioned to shield and accommodate the whole of said compact electron gun therein, the open terminal end of said closed-Wall portion being formed as an aperture-like opening having a ledge instanding from the perimeter thereof to provide a stop for the terminal portion of said encompassed electron gun;

electron gun retaining means formed to fit within said closed wall portion to hold said compact electron gun structure therein in a manner that the forward end of said compact electron gun is positioned against the terminal ledge of said closed-wall portion; and

a plurality of spaced apart lateral support means in the form of dimples and resilient fingers integral with and extending beyond the outer periphery of said skirt portion to elfect centered positioning of said electron gun shielding means within the neck portionof said tube. 2. Electron gun support and shielding means according to claim 1 wherein said skirted annular member has a 5 6 said outer periphery through said skirt into said planar 3,038,094 6/1962 Ney 313-82 RX surface toward said axis. 3,249,790 5/ 1966 Schaefer 313-82 RX R f d FOREIGN PATENTS e e 5 957,027 2/1950 France 313-82 UNITED STATES PATENTS Forgue R Pnmary Examlner Haas 3l3--82 RX 2,864,965 12/1958 U.S. Cl. X.R. Wang 313-82 R 313-242, 254 

